November 19, 2007

There was a lot of hoopla surrounding the controversial suggestion that obesity is "socially contagious" made by Harvard and University of California, San Diego researchers earlier this year. According to this earlier study, if someone’s friend becomes obese, for example, that individual’s chances of becoming obese went up by 57% percent. Among mutual friends, the effect increased up to 171%. The study was the first of it’s kind, and appeared to show a strong correlation between our friend’s waistlines and what we personally find to be a socially acceptable size.

But what if fat wasn’t just “socially” contagious in the form of
attitudes and opinions? What if you could literally be infected with a
“fat” virus? Researcher Nikhal Dhurandhar identified a virus several
years ago that caused chickens to get fatter than uninfected poultry.
Since then researchers have found that a family of related viruses may
also be doing the same thing in humans!

Dhurandhar later teamed up with Dr. Richard Atkinson, president of the
American Obesity Association, to expand the research, particularly to
take a look at how the virus affected humans. The two identified the
"fat virus" as adenovirus Ad-36, one of 50 similar viruses that are
commonly found in humans. Based on his research, Atkinson now believes
these virus plays a role in human obesity. This discovery is especially
intriguing since the explosion of human obesity, in both developed and
poor nations, has led to quite a bit of suspicion that overeating and
inactive lifestyles can’t account for the world’s phenomenal obesity
explosion in such a relatively short amount of time.

“I have devoted my medical career to research, treatment, and teaching
about the disease of obesity. I believe obesity is a complex disease of
many causes, one of which is viral infection,” Atkinson stated.

Earlier this year, researchers in Dhurandhar's lab found that exposure
to the virus actually caused adult human stem cells to turn into
fat-storing cells. Dr. Magdalena Pasarica, who led the study, obtained
adult stem cells from fat tissue of people who had undergone
liposuction. Half of the stem cells were exposed to the virus Ad-36.
After a week, almost all of the infected stem cells had developed into
fat cells, while the uninfected cells were unchanged.

Dr. Leah Whigham of the Dept of Nutritional Sciences, Wisconsin
University agrees that the obesity phenomenon could, in part, be due to
an infectious virus that can be passed from person to person. Whigham
says people are a lot more comfortable believing that lack of control
is the only explanation for being fat. However, she points out, ulcers
used to be attributed to stress, but scientists now know that the virus
H. pylori is a factor. In total, Whigham says there are three viruses
that have been identified as causing chickens—and most likely humans—to
be fatter. In some studies, humans with a high Body Mass Index were
found to be five times more likely to have antibodies to Ad-36, than
those who were not obese. Whigham, Dhurandhar and others are interested
in finding out how many of the other roughly 50 adenoviruses common to
humans could possibly pose this threat, as well.

So how does the Ad-36 virus make chickens and/or people fat? Whigham’s
research shows that the viruses appear to cause the amount of fat
carried in each cell to increase. However, someone can be a carrier of
the virus and not be obese, Whigham points out. But at this point, no
one knows how much of a role the virus plays into weight, so we should
still regard diet and exercise as the primary regulators of weight,
warns Whigham. Even so, researchers are planning on developing a “fat”
vaccine that targets these viruses.

In other words, yes, it is quite scientifically feasible that fat is
literally, and not just socially, contagious. It is scientifically
possible that Ad-36 and similar viruses, contribute to the number on
our bathroom scales. In the future, dieticians may well include “wash
your hands” along with their standard “eat right, and exercise” advice.
Further research will likely shed more light on the subject.